#!/usr/bin/perl -w

use strict;

my @packets=('abcdef','123456','abc123');
my $size;
for $size(2..4){
  print "size=$size\n";
  my %substrs;
  my $packet;
  foreach $packet(@packets){
    my %data;
    for(0..(length($packet)-$size)){
      $data{substr($packet,$_,$size)}=1;
    }
    my $k;
    foreach $k(keys %data){
      if(defined $substrs{$k}){
        $substrs{$k}++;
      }else{
        $substrs{$k}=1;
      }
    }
  }

  foreach((sort {$substrs{$b} <=> $substrs{$a}} keys %substrs)[0..5]){
    print "$_  $substrs{$_}\n";
  }
}